Paintbrush and synthetic bristles for the same



May 23, 1950 J. REIS, JR

PAINTBRUSH AND SYNTHETIC BRISTLES FOR THE SAME 2 Sheets-Sheet 1- Filed Dec. 28, 1944 May 23, 1950 J, J, s, JR 2,508,799

PAINTBRUSH AND SYNTHETIC BRISTLES FOR THE SAME,

Filed Dec. 28, 1944 2 Sheets-She et z Patented May 23, 1950 PAINTER-USE AND SYNTHETIC BRISTLES FOR THE SAME Joseph J. Reis, Jr., Baltimore, Md., assisnor to Pittsburgh Plate Glass Company,

County,

Allegheny la., a corporation of Pennsylvania Application December 28, 1944, Serial No. 570,146

7 Claims.

The present invention relates to synthetic bristles as substitutes for animal bristles in brushes, such as paint brushes and the like, and it has particular relation to brushes comprising synthetic bristles of cellulosic esters such as cellulose diacetate or cellulose triacetate, etc.

One object of the invention is to provide bristles which when assembled in a brush have a high capacity for retaining paint without runmng or spattering during brushing operations and which have properties more satisfactory for brushes generally than those heretofore employed.

A second object is to provide bristles which when assembled in a brush have relatively uniform resiliency in all directions in which the brushes are likely to be moved.

A third object is to provide an improved method of forming bristles of the foregoing character.

These and other objects of the invention will be apparent from consideration of the following specification and claims.

For better understanding of the invention, reference may be had to the drawings in which:

Fig. 1 is a sectional view of a brush constructed in accordance with the provisions of the invention.

Fig. 2 is a diagrammatic or schematic view Bf an apparatus suitable for use in the spinning of bristles embodying the provisions. of the invention.

Figs. 3 and 4 are sectional views showing, on an enlarged scale, sections of bristles taken respectively upon the lines III-III and IVIV of Fig. 6.

Fig. 5 is a fragmentary portion of a filament embodying a plurality of bristle sections before they are cut to length.

Fig. 6 is an elevational view of a single bristle cut from a filament.

Fig. 7 is a detail view of a plate having a plurality of spinnerette openings formed therein, said Openings being of a shape to accord with the principles of the present invention.

Fig. 8 is a side elevational view of the plate shown in Fig. 'I.

In the drawings, like numerals refer to like parts throughout.

As is well known, brushes such as are employed in the spreading of paint and other coating compositions conventionally are formed of animal bristles or hairs grouped together into brush or bristle portions and suitably attached to a bandle. Animal bristles for such brushes, at least of the better types, are relatively circular in sec- 2 tip. The tips may also be substantially frayed or flagged. Thesurfaces further are usually covered with or formed of overlapping plates or scales, which retain paint or other coating material when the brush is dipped therein with a minimum tendency of the paint to spatter or run back down the handle whenthe brush is tipped upwardly. Since the bristles are substantially round in section, they also have approximately similar brushing characteristics in all di= rections.

tionand are also tapered from butt portion to As a result of world-wide conditions, bristles of high grade are now very diflicult, if not impos- 'sible, to obtain and even under normal conditions, the supply and prices thereof are subject to wide fluctuations. Accordingly, it has been proposed to form bristles suitable for paint brushes or similar brushes by spinning filaments of a plastic material such as cellulose triacetate or nylon into long filaments or strands adapted to v be cut up into lengths appropriate for assembly as bristles in brushes.

Much dimculty has been experienced in thus obtaining synthetic bristles which sumciently approximate the natural products in all of their properties. Particular dlfllculty is experienced in obtaining a bristle which will retain an adequate quantity of paint or other coating material when a brush embodying the bristles is dipped therein and which after the brush has been charged, is not subject to excessive tendency to spatter or run. In order to improve the paint retaining characteristics of the bristles, it has been proposed to roughen the surface, especially the tip portions, by contacting the bristles either before or after assembly into brushes with an abrasive wheel or other bufling agency. Such operations obviously require considerable labor and are comparatively expensive. Also, it is relatively dimcult by bufllng to obtainadequate contact of the buiflng a ency with the bristles disposed in the center of the brush.

In my copending application Serial No. 524,666 of March 2, 1944, now Patent No. 2,443,055, entitled Brushes embodying synthetic bristles, it is proposed to form tapered bristles of dumbbell or kidney section. These bristles are designed to leaf together and provide capillary channels of exceptional paint retaining capacity in the brushes. Brushes embodying such bristles are a great improvement over prior types. However, it will be apparent that when a bristle whose width greatly exceeds its thickness is brushed over a surface in a direction parallel to its width, there is a tendency for it to twist or turn about 2,508,799 3 4 a longitudinal axis. This may break or disturb pump may be of any form, for example that the capillary effects, thus promoting irregular described in the patent applications of John J. flow or even spattering of the paint. Gregory, Serial Numbers 459,251, now Patent No. In accordance with the present invention, it is 2,374,744, and 459,252 filed September 22, 1942, proposed to provide brushes of even better brush 5 now abandoned. Since this pump is not a part ing characteristics by forming them of bristles, of the present invention, it is not described in the butt portions of which are of kidney or dumbdetail. The pump is connected by conduits In to hell section designed to retain a large amount a source of solution of a plastic suitable for of paint, and the tips of which are so shaped as spinning, e. g. cellulose triacetate, and is conto present sections in which the ratio of width nected by means of a suitable conduit II with to thickness is practically unity. These bristles, the spinning head i2 disposed in a trough l3 brush much more nearly uniformly in all direccontaining a setting agency such as mineral tions than bristles which are kidney or dumbbell spirits. shaped throughout their length. The spinning head I2 is provided with a plate The conditions of operation as disclosed in this I6 having a multiplicity of small spinner head copending application may be employed in the openings therein. Preferably, these openings are preparation of bristles of varying sections in acof a section corresponding to that desired in the cordance with the provisions of the present intip portions of the bristles. For example, they vention. may be trefoil to provide a trefoil tip portion A convenient method of forming the improved which is found to be of excellent brushing charbristles involves spinning them in the manner acteristics. Usually, there will be a large number described in my prior application or in Haux of these openings varying within the range of application, Serial Number 538,278, filed June 1, about 200 to 400. In Fig. '7, a few of these open- 1944, and entitled Synthetic brush bristle, now ings are shown. Of course, it is impossible for abandoned. However, in order to obtain bristles practical reasons to illustrate the actual number having lobate tips of substantially equal thickor the actual size because of the smallness of the ness and width and butts of greater width than scale of the drawings. It is to be noted that each thickness in accordance with the provisions of plate is, as shown in Fig. 8, cupped and is prothis invention, a spinner plate having lobate, vided with a flange 15 for fastening to the spine. g. trefoil, openings is employed. A pulsating ning head.

pressure is employed to spin the bristle thread The filaments after setting in the bath are or filament at approximately constant speed. The collected into a, bunch or cable and passed over a filament is thus formed with alternate constrictsuitable pulley Iii and then upwardly about a ed and enlarged portions corresponding to the series of take-up rollers H which may be driven tips and butts of the bristles. at a constant speed in order to maintain suf- Surprisingly, it is found that when the bristles ficient tautness in the reach of filaments in the are spun through plates having openings of such setting bath. From the take-up rollers, the filacontour and the solvent removed, the tip portions ments pass to drying chamber H! which may be assume contours corresponding to the openings of any convenient design. Here, heat is supplied of the spinner plates, while the butt portions to drive off all non-solvent and setting agent become flattened out approximately to dumbbell clinging to or absorbed in the body of the filaor kidney sections closely resembling the secment. tions of the bristles disclosed in my prior appli- It is to be noted that the filaments as they cation above mentioned. are spun out are joined together in continuous Each bristle, asshown in Figs. 3, 4 and 6, com- 5 length as they are received from the drying prises a butt portion constituting approximately apparatus. Each filament comprises alternating A; to the length of the bristle and being of a thick portions 22 and restricted portions 23 cordumbbell or kidney shaped section, of a width 2 responding respectively to the butts and the tips or 3 times as great as the thickness, approximately of the bristles which are cut from the filaments. corresponding to the sections of the bristles as e e a ing thic ned and c nst po disclosed in my prior Patent No. 2,443,055 above tions are produced by the pulsation of the presalluded to. The section of this portion is illussure generated by the pump 9. In the drawings, trated as taken along the line III-III of Fig. 6 no particular attempt has been made to repreand the shape of a typical example is shown in sent the bristles and their actual thickness, since Fig. 3. The tip portion of the bristle constitutes they obviously are too small in diameter for accuapproximately A to the total length and rate representation in this manner. Probably, should be of a section in which the width and they will be of an average denier of 20 to 4000. thickness taken in any direction transverse of the After drying, the filaments are passed about bristle are approximately equal. It is desired pulleys or drums 24 and 25 of a mechanism that the section will be lobate in order to provide no design to cut them into sections through their narrow channels or grooves designed to feed the, thickest portions in such manner that each secpaint, varnish or the like liquids retained in the tion includes two lengths of bristles. A suitable capillary tubes above. Aconvenient section may mechanism for automatically performing the be treiold such as that illustrated in Fig. 4 which cutting operation is disclosed in the patent appliis taken approximately upon the line IVIV of cation of John J. Gregory, Serial No. 499,264,

Fig, 6, filed August 19, 1943, now Patent No. 2,356,841.

The sectional area of the butts with respect to The bristles are gathered in bunches of approthe tip will be about 1.75. However, there may priate 'size and are then secured in any conbe considerable variation. By regulation of the venient mannerfor example, by means of paper maximum and minimum in the pressure cycle, bands for transmission to the brush makers.

the desired ratio is obtained. The bristles may be formed of cellulose diace- An apparatus for the spinning operation is tate, cellulose acetobutyrate or other plastics,

shown in Fig. 2 and embodies a pulsating pump which can be dissolved to provide fluid, spinnable apparatus 9 for delivering a solution of cellulosic solutions, but at the present time it is preferred ester under pressure to a spinner head. The to form them of cellulose triacetate from a. soluasoano tion of the type described in my above mentioned co-pending Patent No. 2,443,055. The solution of plastic may, for example, comprise a percent solution, or thereabouts, of cellulose triacetate (60.8 percent acetyl) in a mixture comprising 90 percent methylene chloride and 10 percent of ethyl or methyl alcohol. This solution, as it is spun from the spinnerettes, may be coagulated in a' bath of hydrocarbon such as toluene, xylene or kerosene. Mixtures of'two or three or more of the coagulants may be employed.

It is remarkable that in the spinning operation, the tip portions or restricted portions of the filaments retain the shape, though of course on a smaller scale, of the spinnerettes through which they are emitted. However, the butt portion of the bristles constituting from to 94 of the total length inmost cases assumes a kidney or dumbbell section such as that illustrated in Fig. 3 of the drawings, in which the ratio of the width to the thickness is approximately of the order of 1 to 2 or 1 to 3 /2.

The assembly of the improved bristles into a brush such as that illustrated in Fig. 1 of the drawings may follow substantially any convenient procedure. The bristles may be collected together in bunches of assorted sizes in order to give any desired brush characteristics to the ultimate product. It is also apparent that the synthetic bristles, as thus obtained, may be admixed with any desired ratio of natural bristles, such as pig bristles, ox hair, horse hair or the like, which may be employed in the manufacture of bristles.

A convenient mode of preparing a brush as that represented in Fig. 1 of the drawings involves bunching the bristles together to form a brush portion 36 of suitable size and outline, then inserting the butt portions of the bristles with spacer strips or bars 31 in place in a conventional sheet metal ferrule 38. The. assembly of bristles and spacer strips in the ferrule preferably are impregnated in rubber or other adhesive material in order to effect a bond. The cementing material can be cured by heat or other means in order to obtain thorough hardening with resulting complete bondings of the bristles and'spacer elements. The butt portion of the handle ll is inserted in the upper end of the ferrule and for purposes of security, nails 42 are driven through the ferrule end of the butt portion of the handle. Similar nails may also be driven into the butt portions of the bristles of the brush 36 in order brushes comprising a filament of bristle length and being formed of synthetic plastic and being tapered from butt to tip and having a butt portion of a width of 2 to 3% times the thickness and a lobate tip portion of approximately equal width,

and thickness.

2. A brush bristle suitable for use in paint brushes comprising a filament of bristle length and being formed of cellulose plastic and being tapered from butt to tip and having a butt portion of a width of 2 to 3 /2 times the thickness and a lobate tip portion of approximately, equal width and thickness.

3. A brush bristle suitable for use in paint brushes comprising a filament of bristle length and being formed of cellulose acetate and being tapered from butt to tip and having a butt portion of to the total length and of a width of 2 to 3 times the thickness and a lobate tip portion of approximately equal width and thickness.

4. A brush bristle suitable for use in paint brushes comprising a filament of bristle length and being formed of cellulose triacetate and being tapered from butt to tip and having a butt portion of to A, the total length and of a width of 2 to 3 times the thickness and a lobate tip to provide greater security of the bristles in the handle.

It is to be understood that th dumbbell or kidney sectioned butts of the bristles tend to leaf together in the manner described in my copending application, so that the concave faces provide capillary tubes that readily take up and hold paint or varnish.

The forms of the invention herein shown and described are to be regarded merely as exemplary and it will b apparent to those skilled in the art that numerous modifications may be made therein without departure from the spirit of the invention or the scope of the appended claims.

I claim:

1. A brush bristle suitable for use in paint portion of approximately equal width and thickness.

5. A brush comprising a handleand having a bristle portion secured thereto comprising bristles each of which consists of a filament of bristle length, said filament being formed of cellulose plastic and being tapered from butt to tip, the butt portion being channeled and of a width from 2 to 3 times the thickness, the tip portion being lobate and of approximately equal width and thickness.

6. A bristle suitable for use in forming paint brushes, said bristle being composed of synthetic plastic and being tapered from butt to tip, the butt portion 'being of a thickness of approximately V; the width, the tip portion being of trefoil section.

7. A paint brush having a brush portion comprising bristles of synthetic plastic, the bristles being tapered from butt to tip and having base portions of approximately kidney shape and tip portions of trefoil section.

- JOSEPH J. REIS, JR.

REFERENCES CITED The following references are of record in the file of this patent: 

1. A BRUSH BRISTLE SUITABLE FOR USE IN PAINT BRUSHES COMPRISING A FILAMENT OF BRISTLE LENGTH AND BEING FORMED OF SYNTHETIC PLASTIC AND BEING TAPERED FROM BUTT TO TIP AND HAVING A BUTT PORTION OF A WIDTH OF 2 TO 3 1/2 TIMES THE THICKNESS AND A LOBATE TIP PORTION OF APPROXIMATELY EQUAL WIDTH AND THICKNESS. 